Environmentalist Vincent Salafia today lost his challenge to the routing of the proposed M3 motorway near the Hill of Tara in Co Meath.
Mr Salafia argued that the route would interfere with the historically and archaeologically important valley around the hill.
At the High Court in Dublin today, Judge Thomas Smyth said there was no evidence to support Mr Salafia's belief that the valley was a national monument.
"None of it bore out the belief that there is a national monument that exists, has been damaged or is likely to exist or likely to be damaged," he said. He said Minister for the Environment Dick Roche had been correct to give permission for archaeological work to begin on the motorway last May.
The court heard that archaeologists working on the section of the M3 between Dunshaughlin and Navan had discovered 38 sites of interest within 1.5 kilometres of the route, but none of them were designated as national monuments.
In a two-and-a-half hour judgement, Judge Smyth said Mr Salafia's two-year delay in taking the legal challenge against the state was unjustifiable.
The campaigner told the court that he had been unable to take part in the oral hearings on the motorway held by an Bord Pleanala because he was pre-occupied with the campaign to prevent the route of the M50 motorway going through Carrickmines Castle in Dublin.
"As an explanation or excuse for delaying bringing judicial review proceedings in court... I find this defence wholly unconvincing," said Judge Smyth.
He said that whether a person was a concerned citizen or a professional protester, the obligation to act promptly remained, and he criticised Mr Salafia for appearing to do nothing but write letters about the motorway to newspapers.
He said it was completely unrealistic for Mr Salafia to tell the court that the motorway could be completed on time with a changed route.
He added that the preferred route supported by Mr Salafia had been ruled by experts to be archaeologically unacceptable and alarming. Mr Salafia's legal team had argued that Mr Roche had used the wrong section of the National Monuments Act in making his decision to allow archaeological work to go ahead and also that the act itself was unconstitutional.
But Judge Smyth said Mr Salafia had failed to demonstrate that the balance struck between the protection of national monuments and the permission to build roads was constitutionally invalid. He said it was significant the constitutionality of the act was being challenged by someone living outside the Tara /Skyrne area.
He ruled that Mr Salafia was not locus standi (entitled to be heard) and said it seemed wholly inappropriate to seek to unravel the whole affair some years after the route had been selected.
Mr Salafia, who is studying for a masters in law at Trinity College Dublin, expressed disappointment at the judgement but made no further comment.
The judgement was welcomed by the local businesses in the Meath area and the National Roads Authority. "I think it's an appropriate judgement, it highlights the hard work and expertise that's gone into road planning by the National Roads Authority," said its senior archaeologist Daire O'Rourke.
The Dunshauglin Chamber of Commerce said the M3 motorway was urgently needed to relieve the chronic traffic congestion on the existing N3 route through the town. "People are getting up at all hours, they're spending unnecessary hours in cars. It's bad for their family life, their community and their health," said president Adrienne Bowen.
She said the High Court judgement against Mr Salafia was so emphatic that she would be very surprised if he appealed it to the Supreme Court.